Comparison of Flower Cold Hardiness: Which Ones Tolerate Freezing and Which Fear the Cold

Flowering plants in all their endless variety come from every corner of the globe, and because the climatic conditions of their places of origin differ greatly, their cold hardiness also differs considerably. The cold hardiness of various flowers is tied to the question of how to bring them safely through the winter, so it must be firmly understood, otherwise they will freeze and die. According to the degree of cold hardiness, flowers can be divided into the following three major categories:

(1) Cold-hardy flowers. Most of these flowers originate in temperate, north temperate and subarctic regions, and can overwinter safely outdoors in northern China. Examples include deciduous flowering shrubs and vines such as Japanese honeysuckle, Chinese trumpet creeper, rose, rugosa rose, crape myrtle, rose of Sharon, lilac, winter jasmine, forsythia, flowering almond, Manchu cherry, false spirea, mock orange, flowering quince, Boston ivy and wisteria, as well as evergreen ornamental trees such as Chinese juniper, Chinese arborvitae, littleleaf box, ginkgo and creeping juniper, and perennial and bulbous herbaceous flowers such as hosta, lycoris, daylily, New York aster and hollyhock.

(2) Semi-cold-hardy flowers. Most of these flowers originate in warm temperate regions and can overwinter safely outdoors in the Yangtze River basin of China. In northern North China, the Northeast and the Northwest, when grown outdoors they need soil mounding or straw wrapping for winter protection, and potted ones need to be moved into a cold room or cellar to overwinter. Their aboveground plants cannot endure the severe winter cold of the north, or fear the attack of cold dry winds, otherwise the branches will dry out. These flowers mainly include deciduous flowering trees and shrubs such as Chinese rose, tree peony, ornamental peach, Japanese apricot, wintersweet, pomegranate and fig, as well as evergreen trees and shrubs such as Banks' rose, star jasmine, oleander, magnolia, windmill palm, dragon juniper, deodar cedar, Chinese incense cedar and five-needle pine, and perennial and bulbous flowers such as chrysanthemum, Chinese peony, phlox, purple loosestrife, water lily, water hyacinth, hyacinth and gladiolus.

(3) Non-cold-hardy flowers. These flowers all originate in tropical and subtropical regions and cannot overwinter outdoors in the north; in winter they must be moved into a greenhouse for care, or their underground bulbs dug up and stored in a warm room. These flowers mainly include perennial evergreen herbaceous flowers such as lucky bamboo, spiderwort, spider plant, begonia, asparagus fern, asparagus, calla lily, clivia, bird of paradise and cacti and succulents, as well as evergreen woody flowers such as sago palm, Chinese fan palm, rubber tree, Swiss cheese plant, Chinese hibiscus, jasmine, white champaca, banana shrub, Norfolk Island pine, lantana, night jasmine and bleeding glorybower, and bulbous flowers such as canna, banana, tuberose, cyclamen, amaryllis, narcissus and freesia.